Successful endosseous implants date from about 1968, at which time a biocompatible metal blade was fitted into a prepared elongated receptor site. The blade itself was perforated or vented to allow bone and blood vessels to reunite readily. A projecting metal head, either unitary with or detachable from the blade, provided an anchor for attachment of a fixed bridge. Another endosseous metal implant design is the basket type having a projecting metal head. This implant is used specifically for partial support of a fixed bridge. Neither the blade nor the basket implant is designed or adapted for use as an anchor for overdentures or for use as a freestanding single tooth replacement to support a single crown.
There are at present a number of different dental implant systems in use. Most systems include an artificial root portion or implant cylinder which is placed into a custom bored hole in the jaw bone. A prosthetic coronal section is attached to the artificial root portion when healing and bone integration of the artificial root portion is complete, and a dental prosthetic appliance such as a crown, denture, partial denture or bridge is attached to the coronal section. The prosthetic coronal section must pass through the connective tissue and overlying mucosa for attachment to the prosthesis.
A problem with attachment systems is that of adjusting for undesirable placement angulation of the submerged artificial root. Since the prosthetic coronal section or post normally extends coaxially from the artificial root, and the prosthesis must be mounted on this post, undesirable angulation may make it difficult to align the prosthetic teeth with natural tooth line, particularly for a single tooth. This is a particular problem with front teeth, since for cosmetic reasons it is desirable that a screw or the like securing a crown or artificial tooth to the post does not exit through a front face of the tooth. Some attempts for adjusting angulation are provided in various existing systems, for example providing the post or prosthetic coronal section with a bendable neck portion, but this results in a weakened area which is liable to break.
Another alternative is described by Detsch in U.S. Pat. No. 4,854,872. In one embodiment, male and female prisms with hexagonal or octagonal cross-section are suggested for providing fixed, indexed positions between the artificial root and the coronal section or post. In general, the parts of the Detsch system must be set together and secured with a single screw through a coronal section and an intermediate post into the artificial root. This presents the dentist with a multiplicity of parts to be secured.
An object of our invention is to provide an indexable endosseous dental implant system with positive indexing between an artificial root and coronal post with a minimum of separable pieces.
Another object of our invention is to provide the endosseous dental implant with a relatively large number fixable indexed orientations between the artificial root and the coronal section while maintaining a relatively high resistance to torque.
It is a further object of our invention to provide such a system with multiple interlockable indexing formations wherein a first formation can be secured independently from the second formation.
These and other objects of our invention will be apparent from the following description taken with reference to the accompanying drawings.